This section provides background information related to the present disclosure which is not necessarily prior art.
During manufacturing processes, device pressure and flatness need to be monitored daily. Usually a pressure tester is used to test the pressure. However, this kind of pressure testing method has a complicated testing process, and the operation is inconvenient, not suitable for everyday monitoring of device pressure. Moreover, the flatness of the tested device is usually detected by a traditional pressure sensitive film. However, the pressure sensitive film is not sensitive to the pressure values, and cannot be used to monitor the device pressure.